Trucks of aid arrived in the ruined capital of Pakistan-occupied Kashmir on Tuesday, and victims scuffled for badly needed food and blankets three days after a devastating earthquake flattened whole communities, killing tens of thousands and leaving millions homeless.

US military helicopters helped ferry wounded people from the wrecked city of Muzaffarabad, while international rescue teams joined the search for survivors before the window of hope for finding people alive begins to close.

Pakistan's government officially put the death toll at just over 20,000, but local officials estimated much higher fatalities - perhaps twice as high. With winter just six weeks away, the United Nations has said 2.5 million people in the worst-hit areas near the mountainous Pakistan-India border need shelter.

About 10 trucks brought by Pakistani charities and volunteers rumbled into Muzaffarabad early on Tuesday. Attempts by relief workers for an orderly distribution dissolved into chaos as residents scuffled for the handouts of cooking oil, sugar, rice, blankets and tents.

It was the first major influx of aid since the monster 7.6-magnitude quake struck Saturday morning, destroying most homes and all government buildings in this city, and leaving its 600,000 people without power or water. Most have had to spend the three cold nights without shelter.

Two or three police looked on helplessly as more than 200 people raided a stockpile of foodstuffs arranged by relief workers at a soccer field near the city centre- one of six designated aid distribution points in Muzaffarabad.

One man could be seen making off with a big sack of sugar, another left on a motorised rickshaw with a big crate of drinking water.